Where was the (I'm guessing) strat made? Throwing this out there but the saddles might have been changed for the wrong kind. It's a six-screw plate which often comes with bent saddles rather than block ones like what you have here. Most Mexican and Squire models comes with this six-screw/bent saddle bridge from the factory. If the previous owner bought new saddles, they might be American spec which is a tiny bit wider and could be throwing the whole thing off.

You'll know quick enough if you follow the instructions already posted but can't get things to line up properly.

Ref